NUI Galway – UL Alliance First Annual ENGINEERING AND - ARAN ...

Environmental analysis of tidal power
Noreen O’Brien
Environmental Change Institute, Civil Engineering Department
noreenobrien@ireland.com
Abstract
The world’s reliance on fossil fuels needs to be
reduced with the introduction of sustainable energies.
The EU MAREN project hopes to bring together
countries of the Atlantic area to expand the marine
renewable energy sector. Environmental impacts are
one of the issues that need to be analysed and
addressed for marine energy to be a viable source of
energy. Numerical modelling can be used to look into
this issue and model the effects of sediment and solute
transport.
1. Introduction
The EU is part of the Kyoto Protocol and is
committed to reducing their greenhouse emissions by
8% below the 1990 levels. Ireland has a target of 13%
above their 1990 levels. This reduction is to be
achieved in the 2005 – 2012 time period.
Marine energy is one of the areas, which could be
exploited by the island of Ireland for the use of
electricity(Roche, Minister for the Environment et al.
2007)
The countries of the EU interregional Atlantic areas
have come together under the EU funded MAREN
project to optimize the energy potential of the Atlantic.
The main aim of the MAREN project is to optimize the
energy extraction process of marine renewable energy
and do so with the least amount of hydro-environmental
impacts.
2. Offshore energy extraction
Sustainable energy can be harnessed from sources
that are located offshore in the seas and oceans.
Offshore wind farms, wave energy extraction devices
and tidal extraction device are some of the methods that
are used to harness energy from offshore sources.
2.1. Advantages of tidal power
Tidal energy extraction has a few advantages over
the other forms of marine energy extraction processes.
The predictable nature of tides is the main advantage of
this type of energy extraction. The density of water is
greater then air, allows greater amounts of energy to be
captured from tides with same size device used for
wind energy extraction.(Hammons 1993)
3. Environmental impacts
There are a number of different environmental
impacts that can be possible with the marine energy
extraction. The following issues can be affected by
extraction devices: Habitat and ecology, water quality,
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birds, fish, sediment transport, landscape and visual,
ports and navigation, biodiversity, protected areas and
flooding(Commision 2007)
4. Numerical modelling
The flow of fluid is governed by three principals, the
conservation of mass, Newton’s second law and
conservation of energy.(Falconer 1998)
Theses principals are expressed mathematically by
integral and differential equations. There are no
analytical solutions to these. Numerical models, such as
DIVAST, FLUENT and MIKE, replace the integral and
differential part of the equations with discrete algebraic
forms. These equations can then be solved to get values
of the characteristics of the flow field at certain point in
time and space. These methods can give a good insight
into the flow of fluid in certain areas, which are hard to
measure experimentally. Numerical models are also
used for water quality assessment, with the assessment
of solute and sediment transport.
The research project has developed new analysis
techniques with the use of tidal ellipses and the actuator
disk theory. The project will expand its analysis
techniques with the introduction of two-way nested
modeling techniques. (Bockelmann, Fenrich et al.
2004)
5. Conclusion
Tidal power can become one of the leading
sustainable energy’s in Ireland by tackling issues such
as hydro-environmental impacts and optimizing energy
extraction.
7. References
Bockelmann, B. N., E. K. Fenrich, et al. (2004).
"Development of an ecohydraulics model for stream and river
restoration." Ecological Engineering: 227 - 235.
Commision, S. D. (2007). Tidal Power in the UK. S. d.
commision.
Falconer, R. A. (1998). DIVAST. University of Cardiff.
Hammons, T. J. (1993). "Tidal Power." IEEE Journal 8(3):
419-433.
Roche, D., Minister for the Environment, et al. (2007).
National Climate Change Strategy 2007-2012. H. a. L. G.
Department of the Environment.